- Oct 26, 2023

End-Around Taxiways: What are they?

End-Around Taxiway at the southern end of runway 08R at Hartsfield-Jackson Atlanta International Airport (Image by Pond & Company)

With the expansion of Singapore's Changi Airport in full swing, one can expect a dozen new taxiways along with the highly-anticipated Terminal 5 building, which will catapult Changi's passenger handling capacity to more than 150m per year.

As an avgeek, I take a keen eye to the ever-changing landscape of Changi Airport as construction actively progresses each day.

More often than not, the best way to do this is by looking at the updated satellite imagery Google adds every few months onto Maps/Earth.

The satellite images added of the Changi Airport area a few months ago showed some developments, runway 2 (i.e. Runway 02C/20C) looks almost ready for ops (scheduled to open at the end of next month) with upgrading almost completed, along with a system of new taxiways and rapid exit taxiways (RET) that run adjacent on the eastern side of the runway (more on that later).

Changi taking shape: Runway 1 on the left, Runway 2 in the middle and its adjacent taxiways (indicated by the darker-coloured asphalt surfaces), future T5 in the empty patch next to Runway 2, runway 3 on the far right (image by Google)

What was somewhat peculiar, however, was a new taxiway that looks almost completed which extends beyond the southern of runway 02C and loops around:

A closer look at the southern End-Around Taxiway (satellite image by Google)

I thought it was interesting as to why a taxiway was being built that goes around the runway, especially when there is nothing (yet) on the eastern side of the runway.

I decided to do some research into it and found out these taxiways are actually referred to as what is known as End-Around Taxiway(s), a first for Changi.

Purpose

End-Around Taxiway or EATs for short, aim to improve traffic efficiency by allowing aircraft to circumscribe around the active runway instead of getting them to hold short and wait for clearance to cross, which might take up time during peak traffic periods and cause potential delays.

These taxiways are usually built around the end of the runways.

A handful of airports around the world have these purpose-built taxiways with Changi being the latest to implement this interesting network of taxiways.

EATs in practice

To put things into perspective, take a look at Hartsfield-Jackson International Airport in Atlanta, particularly at both the runways 26L and 26R. The runway on the right is 26R and the one on the right is 26L, with taxiway 'B' in the middle:

Runways 26L and 26R at Hartsfield-Jackson Atlanta International Airport (ATL) and taxiway B (highlighted in yellow), with the passenger terminals on the left, as seen on Google Earth

Traditionally, for this specific part of the airport, Atlanta uses a two-runway system; which would mean arrivals would land on the outboard runway (26R) and departures depart from 26L.

With this, arriving aircraft on 26R would have to cross 26L to get to the terminal buildings and gates. If there is a departure on 26L, the aircraft has to hold short on 26L and wait for clearance:

Arrivals on 26R have to hold short of 26L and wait for clearance (green arrow), departures on 26L (yellow arrow)

Having such a system would most definitely cause delays to arriving traffic as they hold short of 26L. Too many aircraft holding short will also cause significant congestion and a queue might form on taxiway 'B'.

To address this, there is an End-Around Taxiway 'Victor' that is built around the end of Runway 26L so that arriving traffic can circumvent Runway 26L:

The route arriving aircraft take upon landing on runway 26R to get to the ramp and passenger terminals at Atlanta, bypassing the need to cross 26L (green arrow)

Southwest 2456 taking the EAT 'V' to get to the gates (image from Flightradar24)

Visual Screens

One important component of the EAT is something called a visual screen. These are installed at the end of the runways where EATs encircle them:

EAT visual screen being built at DFW (image from Blast Deflectors Inc.)

The screen is very distinguishable and recognizable to pilots. It serves an important purpose: it helps the pilot on the runway preparing to takeoff or taking off to distinguish whether the aircraft on the EAT is taxiing on the EAT or crossing the active runway the pilot is on:

A visual of how an aircraft taxiing on an EAT would look to a pilot on the runway (screen capture from FAA's End-Around Taxiway video on YouTube)

How an EAT visual screen would look (screen capture from Blast Deflectors Inc.)

This way, the pilot knows for sure that the aircraft he/she is seeing is in fact, taxiing on the EAT and not crossing the runway.

A visual screen is, however, not needed if the airport terrain conceals the nacelle of the aircraft on the EAT from the pilot's eye-level view (i.e. EAT is lower than the runway).

In the case of Atlanta's Hartfield-Jackson International Airport, End-Around Taxiway 'V' does not have a Visual Screen as there is terrain (bushes) that partially obstructs the view of the EAT from runway 26L thus, there is no need for a visual screen to be implemented:

Terrain blocking the view of End-Around Taxiway 'V' from runway 26L (image from Google Earth)

So, it really depends on whether if the crew can see the aircraft's nacelle or not, according to the FAA.

Singapore's Changi airport, however, does have the EAT visual screen implemented as there are no obstacles that block the view of the operating crew from Runway 20C and with a large number of taxiways that lead to Runway 02C/20C, any plane on the EAT could be potentially mistaken as an aircraft crossing the active runway.

Eat visual screen partially blocking the view on End-Around Taxiway 'L', reflected in the Aerodrome Chart of the CAAS AIP Supplement, 21 Sep 2023

These structures are visible in the earlier satellite images from Google as well:

Eat visual screens and the EAT 'L' that encircles it is seen (satellite images by Google)

It is worth mentioning there is also another set of EATs located on the northern end of Runway 2, along with visual screens. It's mainly being used for departing aircraft to access runway 3 and part of it is still under construction for it to really serve its purpose as a fully functional EAT (will be mentioning them briefly later but wouldn't be going into too much detail on that)

Information about the EATs for both ends reflected under the 'remarks' section of the CAAS AIP Supplement, 21 Sep 2023

Infrastructure at Changi Airport

Satellite image of Changi (image from Google)

Changi currently operates a two-runway system (as of writing) with runway 1 (02L/20R) - highlighted in yellow mostly handling arrivals and runway 3 (02R/20L) handling departures - highlighted in green. Runway 2 is closed and is scheduled to open very soon - highlighted in red.

While arrivals are relatively straight-forward as the 3 terminal buildings are just a short taxi away upon arrival, departures are usually allocated to runway 3, which would mean departing traffic have to taxi on Taxiways 'J' and 'K' to access Runway 3 from the main terminal buildings - highlighted in blue, these are the other set of EATs I've mentioned earlier on the northern side of Runway 2.

The EAT 'L', the focus of this article, at the southern end of runway 2 is highlighted in orange.

The rest of the area between Runway 2 and Runway 3 (marked with stripes) is under construction for the future Terminal 5 and its related facilities including; new taxiways, bays for aircraft to park and other support infrastructure.

End-Around Taxiways in Changi's context: How do they help?

With the specific example of End-Around Taxiway 'L' around runway 02C, it is most likely being built for aircraft to access the future Terminal 5 area and its facilities without actually having to cross the runway itself.

A possible taxi route on 'L' for an aircraft to get to T5 (Aerodrome chart from the CAAS AIP Supplement, 21 Sep 2023)

An aircraft bound for the future terminal 5 arriving on runway 1 (02L/20R) can be asked to taxi on 'L', around runway 2 (highlighted in yellow) instead of joining the queue and waiting for clearance to cross runway 2, significantly reducing delays to get to a gate.

With the addition of 'L', it will reduce possible congestion and separates departing/arriving traffic from traffic crossing the runway just to get to the other side as well.

Whilst it might not seem like much now, such taxiways are part of Changi's expansion plans and will likely play a key purpose in handling more aircraft as demand and capacity increases in the future.